Radio receiving system



April 10, 1928.

P. E. EDELMAN RADIO RECEIVING SYSTEM Filed June 5 1922 fi m m ductionwithout circuit noises.

Patented Apr. 10, 1928.

UNITED STATES PHILIP E. EDELMAN, OF CHICAGO, ILLINOIS.

nanro RECEIVING s srnm.

Application filed .Tune 5,

My invention relates to improvements in a radio receiver suitable forreception of broadcasted programs and the ob ects are to provideimproved circuit arrangements therefor, to obtain improved energypick-up and amplification thereof, increasing the amplification toobtain good volume of repro- I attain these objects by the circuit arranement illustrated by way of example in t e accompanying drawing, inwhich the figure is a diagram ofv a suitable embodiment of my invention."While I am showing a specific example of my invention, various changesmay be made therefrom within the scope of the appended claims.

The incoming radiant energy is picked up preferably by a miniature sizedaerial 1. Aerial 1 can be conveniently accommodated in a room or cabinetin which apparatus is located, and connects via wire 2 to tuningcondenser 4 in series with inductance 17 and 18 comprising a primarywinding of a variometer 5 which is connected to ground 6.

Energy is transferred via coupling 49 of variometer 5 to secondary coils19 and 20 thereof which are in shunt to tuning condenser 3 which ismechanically connected to condenser 4 by mechanical link 10. Variometer5 is arranged as shown so that winding 17 is continuously coupled towindin 20 while winding 18 is continuously coupled to winding 19, and atthe same time a variometer is comprised by coils 17 and 18, also bycoils 19 and 20, so that eflicient energy transfer via coupling. 49 ismaintained for each adjustment of variometer 5.

\Vire 16 and wire 7 connect from coils 19 and 20 as input to vacuum tube8. Condensers 14 and 15 are series connected between wire 7 and grid 21of'vacuum tube 8. Resistances 11 and 12 are shunted around condensers 14and 15. Condensers 14 and 15 are selected of'suitable small capacity andresistances 11 and 12 are made of suitable high resistance. j p

a The plate 29 of vacuum tube 8 connects via wire 9 to resistance 22 andcondenser 24. Resistance 22 connects via wire 30 to terminal 36 of powersupply 40. Condenser 24 tap of power supply 40 such as 29. Coil 1922.Serial No. 566,132.

portion 33 is selected with relatively few turns so that condenser 26can by-pass energy therefrom to the middle junction 13 betweenresistances 11 and 12 via wire 55. Coil portion 33 and condenser 26 canbe selected tov pass either audio frequency or radio frequency energy orboth, it being understood that only a small amount of energy is to befed back to junction 13 to affect grid 21 of the preceding tube 8. Core31 couples primary winding 51 to secondary winding 32 which feeds audiofrequency energy to grid 53 of vacuum tube 54. Plate 52 of vacuum tube54 connects by wire 27 to reproducer 37 which latter connects by wire 28to the highest potential terminal of power supply 40. The negativeterminal of power supply 40 connects at 41 via wire 42 to the filamentsof vacuum tubes 8, 23 and 54. Filament power supply 43 connects via ment57 of vacuum tube 23 and filament 58 v of vacuum tube 54 via wires 45and 44.

v This novel arrangement of circuits produces unusual results. Firstlyit will be observed that the double variometer 5 affords good energytransfer from pick-u circuit 1, 2, 4, 17 18, 6 to the grid circuit 0vacuum tube 8. ometer 5 remains good over the range of adjustments made.Condensers 14 and 15 with resistances 11 and 12 serve several'functionsin transferring energy to grid 21 of vacuum tube 8 so that tube 8 actsin a plurality of urposes, amplifying the ener transferre to it viavariometer 5 as we as energy transferred thereto via wire 55 fromby-pass condenser 26 feeding energy thereto from plate 38 of vacuum tube23. Resistances 11 and 12 also serve to prevent audio frequencyhowl-noises by reducing'the 21 of vacuum tube 8 can operatively handle.Probably some detector action occurs in tube 8 and if incomplete can becompleted by vacuum tube 23, which also operates in a plurality offunctions at 'both radio fre uenand audio frequency current variat ons.

acuum tube 54 serves for audio frequency amplification but thereproducer 37' is prevented from undesired audio whistling reproductionby the expedient of having vacuum tube 8 operated at lower plate voltageThe continuous coupling of vari-.

' current fed via wire 55 to values which grid at lower plate voltagethan vacuum tube 54. Mechanical link 10 serves to effect simultaneouschange of tuning ran e of circuits including condensers 3 an 4. Thevarious circuit constants can be selected as is customary in the artaccording to the range of frequencies to be amplified. Radio frequencycurrents can easily pass via condensers 14 and 15 but are substantiallybarred by resistances l1 and 12, though the latter can pass continuouscurrent or low frequency currents. Grid 21 of vacuum 8 is thus preventedfrom chokiri up with accumulated negative charge or rom being overloadedwith input capable of sustaining audio howl currents. The success ofthis arrangement depends on keeping the value of the currents fed backto the first tube 8 from the second tube 23 to small uantity able tooperate grid 21 without over oading or production of audio frequencyoscillations. Ver good amplification can thusbe had with aithfulreproduction free from ob'ectionable noises howls or squeals.

at I claim is: 1. In a radio receiver including a series 0 vacuum tubeshaving input and output cirlimited amount of output ener plified withoutbuilding up an esired encuits, a grid input circuit for one of saidvacuum tubes, a plate output circuit for another of said vacuum tubessucceeding said first named vacuum tube in said series, and a resistanceconnected to' feed energy from said last named plate output circuit viasaid resistance tothe grid of said first named vacuum tube, whereby alimited amount of said output circuit ener is applied to said grid ofsaid first name vacuum tube under the control of said resistance. 7

2. In a radio receiver including a series of vacuum tubes having inputand output circuits, a grid in ut circuit element for one of said vacuumtu es comprising a resistance in two sections having a common junction,capacity shunted around said resistance, and means to feed a limitedamount of output energy from a succeeding vacuum tube of said series tosaid input circuitvia said common junction.

3. In a radio receiver including a series of vacuum tubes having, inputand output circuits, a grid circuit for one of said vacuum tubesincluding resistance shunted by ca-.

pacity with a tap'connection comprised in said resistance and means tofeed a limited amount of output energy from a succeeding vacuum tube ofvsaid series to said grid circuit via said tap connection whereby said isre-amergy oscillations.

4. In a radio receiver including aseriee of vacuum tubes having inputandoutput circuits successively coupled, a grid circuit for one of saidvacuum tubes arranged to trans fer energy'at both radio and audiofrequencies thereto and including a series connected current controldevice therefor, an output circuit for a succeeding vacuum tube of saidseries having means to by-pass a. portion of the output energy thereofat both radio fre-. quency' and audio frequency to said grid circuit viasaid series connected control device of said grid circuit and limitedunder control thereof whereby a plurality ofenergy amplifications may beobtained via said vacuum tubes under control of said" series controldevice, and an output circuit for said amplified energy.

5. In a radio receiver having a series of vacuum tubes with input andoutput circuits I successively coupled, a grid input circuit for one ofsaid vacuum tubes including a grid current control device to passlimited amounts of input energy at radio and audio frequencies, means tofeed a portion of the output energy from another of said vacuum tubes insaid series to said current control vacuum tubes, a current controldevicecomprised with said input circuit, a coupling between said firstand second vacuum tubes of said series, an output circuit for saidsecond vacuum tube, a condenser connected between said last-named outputcircuit and said current control device to by-pass'l a small amount ofsaid output circuits ener to said control device, a third vacuumtu e ofsaid series connected to saidoutput circuit, a reproducer operated viasaid last named vacuum tube, a common source of' current supply for saidvacuum tubes, and means to energize the plate circuits of each of saidvacuum tubes from said source of current supply at potentialsproportioned to the increasing amount ofenergy amplified in'saidsuccessive vacuum tubes of said series.

In witness whereof I have hereunto-set my hand this third day of June,1922, at New York, New York.

PHILIP E. EDELMAN.

